smite: use BOLT 9 feature bitfield primitives

smite-ir/src/operation.rs

@@ -14,7 +14,7 @@ use std::fmt::Write;
 use bitcoin::{opcodes::all as opcodes, script::Builder, script::PushBytes};
 use rand::{Rng, RngExt};
 use serde::{Deserialize, Serialize};
-use smite::bolt::ShortChannelId;
+use smite::bolt::{FeatureBit, Features, ShortChannelId};
 
 use super::VariableType;
 
@@ -520,56 +520,93 @@ impl ChannelTypeVariant {
 
     /// The feature bits (even/required) contained in this channel type.
     #[must_use]
-    pub fn bits(self) -> &'static [usize] {
-        // BOLT 9 feature bits:
-        //   12 = option_static_remotekey
-        //   22 = option_anchors
-        //   40 = zero_fee_commitments
-        //   46 = option_scid_alias
-        //   50 = option_zeroconf
-        //   80 = option_simple_taproot
-        //  180 = option_simple_taproot_staging
-        // 2022 = option_script_enforced_lease
+    pub fn bits(self) -> &'static [FeatureBit] {
+        use Features as F;
         match self {
-            Self::StaticRemoteKey => &[12],
-            Self::StaticRemoteKeyScidAlias => &[12, 46],
-            Self::StaticRemoteKeyZeroConf => &[12, 50],
-            Self::StaticRemoteKeyScidAliasZeroConf => &[12, 46, 50],
-            Self::Anchors => &[12, 22],
-            Self::AnchorsScidAlias => &[12, 22, 46],
-            Self::AnchorsZeroConf => &[12, 22, 50],
-            Self::AnchorsScidAliasZeroConf => &[12, 22, 46, 50],
-            Self::ZeroFeeCommitments => &[40],
-            Self::ZeroFeeCommitmentsScidAlias => &[40, 46],
-            Self::ZeroFeeCommitmentsZeroConf => &[40, 50],
-            Self::ZeroFeeCommitmentsScidAliasZeroConf => &[40, 46, 50],
-            Self::SimpleTaproot => &[80],
-            Self::SimpleTaprootScidAlias => &[80, 46],
-            Self::SimpleTaprootZeroConf => &[80, 50],
-            Self::SimpleTaprootScidAliasZeroConf => &[80, 46, 50],
-            Self::SimpleTaprootStaging => &[180],
-            Self::SimpleTaprootStagingScidAlias => &[180, 46],
-            Self::SimpleTaprootStagingZeroConf => &[180, 50],
-            Self::SimpleTaprootStagingScidAliasZeroConf => &[180, 46, 50],
-            Self::ScriptEnforcedLease => &[12, 22, 2022],
-            Self::ScriptEnforcedLeaseScidAlias => &[12, 22, 2022, 46],
-            Self::ScriptEnforcedLeaseZeroConf => &[12, 22, 2022, 50],
-            Self::ScriptEnforcedLeaseScidAliasZeroConf => &[12, 22, 2022, 46, 50],
+            Self::StaticRemoteKey => &[F::OPTION_STATIC_REMOTEKEY],
+            Self::StaticRemoteKeyScidAlias => &[F::OPTION_STATIC_REMOTEKEY, F::OPTION_SCID_ALIAS],
+            Self::StaticRemoteKeyZeroConf => &[F::OPTION_STATIC_REMOTEKEY, F::OPTION_ZEROCONF],
+            Self::StaticRemoteKeyScidAliasZeroConf => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_SCID_ALIAS,
+                F::OPTION_ZEROCONF,
+            ],
+            Self::Anchors => &[F::OPTION_STATIC_REMOTEKEY, F::OPTION_ANCHORS],
+            Self::AnchorsScidAlias => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_ANCHORS,
+                F::OPTION_SCID_ALIAS,
+            ],
+            Self::AnchorsZeroConf => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_ANCHORS,
+                F::OPTION_ZEROCONF,
+            ],
+            Self::AnchorsScidAliasZeroConf => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_ANCHORS,
+                F::OPTION_SCID_ALIAS,
+                F::OPTION_ZEROCONF,
+            ],
+            Self::ZeroFeeCommitments => &[F::ZERO_FEE_COMMITMENTS],
+            Self::ZeroFeeCommitmentsScidAlias => &[F::ZERO_FEE_COMMITMENTS, F::OPTION_SCID_ALIAS],
+            Self::ZeroFeeCommitmentsZeroConf => &[F::ZERO_FEE_COMMITMENTS, F::OPTION_ZEROCONF],
+            Self::ZeroFeeCommitmentsScidAliasZeroConf => &[
+                F::ZERO_FEE_COMMITMENTS,
+                F::OPTION_SCID_ALIAS,
+                F::OPTION_ZEROCONF,
+            ],
+            Self::SimpleTaproot => &[F::OPTION_SIMPLE_TAPROOT],
+            Self::SimpleTaprootScidAlias => &[F::OPTION_SIMPLE_TAPROOT, F::OPTION_SCID_ALIAS],
+            Self::SimpleTaprootZeroConf => &[F::OPTION_SIMPLE_TAPROOT, F::OPTION_ZEROCONF],
+            Self::SimpleTaprootScidAliasZeroConf => &[
+                F::OPTION_SIMPLE_TAPROOT,
+                F::OPTION_SCID_ALIAS,
+                F::OPTION_ZEROCONF,
+            ],
+            Self::SimpleTaprootStaging => &[F::OPTION_SIMPLE_TAPROOT_STAGING],
+            Self::SimpleTaprootStagingScidAlias => {
+                &[F::OPTION_SIMPLE_TAPROOT_STAGING, F::OPTION_SCID_ALIAS]
+            }
+            Self::SimpleTaprootStagingZeroConf => {
+                &[F::OPTION_SIMPLE_TAPROOT_STAGING, F::OPTION_ZEROCONF]
+            }
+            Self::SimpleTaprootStagingScidAliasZeroConf => &[
+                F::OPTION_SIMPLE_TAPROOT_STAGING,
+                F::OPTION_SCID_ALIAS,
+                F::OPTION_ZEROCONF,
+            ],
+            Self::ScriptEnforcedLease => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_ANCHORS,
+                F::OPTION_SCRIPT_ENFORCED_LEASE,
+            ],
+            Self::ScriptEnforcedLeaseScidAlias => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_ANCHORS,
+                F::OPTION_SCRIPT_ENFORCED_LEASE,
+                F::OPTION_SCID_ALIAS,
+            ],
+            Self::ScriptEnforcedLeaseZeroConf => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_ANCHORS,
+                F::OPTION_SCRIPT_ENFORCED_LEASE,
+                F::OPTION_ZEROCONF,
+            ],
+            Self::ScriptEnforcedLeaseScidAliasZeroConf => &[
+                F::OPTION_STATIC_REMOTEKEY,
+                F::OPTION_ANCHORS,
+                F::OPTION_SCRIPT_ENFORCED_LEASE,
+                F::OPTION_SCID_ALIAS,
+                F::OPTION_ZEROCONF,
+            ],
         }
     }
 
     /// Encodes the channel type as a BOLT feature bitmap (big-endian bytes).
     #[must_use]
-    #[allow(clippy::missing_panics_doc)] // bits() is always non-empty
     pub fn encode(self) -> Vec<u8> {
-        let bits = self.bits();
-        let max_bit = *bits.iter().max().expect("non-empty bits");
-        let num_bytes = max_bit / 8 + 1;
-        let mut out = vec![0u8; num_bytes];
-        for &bit in bits {
-            out[num_bytes - 1 - bit / 8] |= 1 << (bit % 8);
-        }
-        out
+        Features::from_bits(self.bits()).into_bytes()
     }
 }
 

smite-scenarios/src/executor.rs

@@ -9,8 +9,8 @@ use bitcoin::{OutPoint, ScriptBuf, Txid};
 use smite::bitcoin::{BitcoinCli, TxBlockPosition, Utxo};
 use smite::bolt::{
     AcceptChannel, AnnouncementSignatures, ChannelAnnouncement, ChannelId, ChannelReady,
-    ChannelReadyTlvs, ChannelUpdate, FundingCreated, FundingSigned, Message, NodeAnnouncement,
-    OpenChannel, OpenChannelTlvs, Pong, ShortChannelId, Shutdown, msg_type,
+    ChannelReadyTlvs, ChannelUpdate, Features, FundingCreated, FundingSigned, Message,
+    NodeAnnouncement, OpenChannel, OpenChannelTlvs, Pong, ShortChannelId, Shutdown, msg_type,
 };
 use smite::channel_tx::{
     ChannelConfig, ChannelPartyConfig, ChannelState, FundingTransaction, HolderIdentity, Side,
@@ -932,7 +932,7 @@ fn build_funding_created(
     let config = ChannelConfig {
         funding_outpoint,
         funding_satoshis: open_channel.funding_satoshis,
-        channel_type: open_channel.tlvs.channel_type.clone().unwrap_or_default(),
+        channel_type: Features::from(open_channel.tlvs.channel_type.clone().unwrap_or_default()),
         opener,
         acceptor,
         minimum_depth: accept_channel.minimum_depth,

smite-scenarios/src/scenarios/setup.rs

@@ -2,7 +2,7 @@
 
 use std::time::Duration;
 
-use smite::bolt::{Init, InitTlvs, Message};
+use smite::bolt::{FeatureBit, Features, Init, InitTlvs, Message};
 use smite::noise::NoiseConnection;
 use smite::scenarios::ScenarioError;
 
@@ -30,49 +30,34 @@ pub trait SnapshotSetup<T: Target> {
     fn setup(target: &T) -> Result<(NoiseConnection, ProgramContext), ScenarioError>;
 }
 
-/// Clears a feature bit from a feature vector.
-///
-/// Feature vectors are encoded as big-endian byte arrays where bit N lives in
-/// byte `features[len - 1 - N/8]` at position `N % 8`.
-fn clear_feature_bit(features: &mut [u8], bit: usize) {
-    let byte_index = features.len().checked_sub(1 + bit / 8);
-    if let Some(i) = byte_index {
-        features[i] &= !(1 << (bit % 8));
-    }
-}
-
-/// Gossip-related feature bits (BOLT 9): `gossip_queries` (6/7),
-/// `gossip_queries_ex` (10/11). Stripped so the target doesn't send
-/// `gossip_timestamp_filter` or other gossip noise during execution.
-const GOSSIP_FEATURE_BITS: &[usize] = &[6, 7, 10, 11];
-
-/// Feature bits that force a dual-funded flow when both peers support them:
-/// `option_dual_fund` (28/29). Eclair in particular will not allow
-/// single-funded flows if either of these feature bits is set, so we strip them
-/// when fuzzing the single-funded flow.
-const DUAL_FUNDING_FEATURE_BITS: &[usize] = &[28, 29];
-
-/// Peer storage feature bits: `option_provide_storage` (42/43). When enabled,
-/// peers may send `peer_storage` and `peer_storage_retrieval` messages at
-/// arbitrary times. Disabling these bits eliminates peer storage noise.
-const PEER_STORAGE_FEATURE_BITS: &[usize] = &[42, 43];
+/// Features stripped from our echoed `init` so the target stays on the single
+/// funded flow and doesn't emit unrelated noise:
+/// - `gossip_queries` (6/7), `gossip_queries_ex` (10/11): Stripped so the
+///   target doesn't send `gossip_timestamp_filter` or other gossip noise during
+///   execution.
+/// - `option_dual_fund` (28/29): Eclair in particular will not allow
+///   single-funded flows if either of these feature bits is set.
+/// - `option_provide_storage` (42/43): When enabled, peers may send
+///   `peer_storage` and `peer_storage_retrieval` messages at arbitrary times.
+const STRIPPED_FEATURES: &[FeatureBit] = &[
+    Features::GOSSIP_QUERIES,
+    Features::GOSSIP_QUERIES_EX,
+    Features::OPTION_DUAL_FUND,
+    Features::OPTION_PROVIDE_STORAGE,
+];
 
 /// Creates an `init` that echoes the received features with bits stripped that
 /// would steer the target away from the single-funded `open_channel` flow.
 fn init_for_single_funded(received: &Init) -> Init {
-    let mut globalfeatures = received.globalfeatures.clone();
-    let mut features = received.features.clone();
-    for &bit in GOSSIP_FEATURE_BITS
-        .iter()
-        .chain(DUAL_FUNDING_FEATURE_BITS)
-        .chain(PEER_STORAGE_FEATURE_BITS)
-    {
-        clear_feature_bit(&mut globalfeatures, bit);
-        clear_feature_bit(&mut features, bit);
+    let mut globalfeatures = Features::from(received.globalfeatures.clone());
+    let mut features = Features::from(received.features.clone());
+    for &bit in STRIPPED_FEATURES {
+        globalfeatures.clear_feature(bit);
+        features.clear_feature(bit);
     }
     Init {
-        globalfeatures,
-        features,
+        globalfeatures: globalfeatures.into_bytes(),
+        features: features.into_bytes(),
         tlvs: InitTlvs::default(),
     }
 }

smite/src/bolt.rs

@@ -14,6 +14,7 @@ mod closing_complete;
 mod closing_sig;
 mod commitment_signed;
 mod error;
+mod features;
 mod funding_created;
 mod funding_signed;
 mod gossip_timestamp_filter;
@@ -52,6 +53,7 @@ pub use closing_complete::{ClosingComplete, ClosingTlvs};
 pub use closing_sig::ClosingSig;
 pub use commitment_signed::{CommitmentSigned, CommitmentSignedTlvs};
 pub use error::Error;
+pub use features::{FeatureBit, Features};
 pub use funding_created::FundingCreated;
 pub use funding_signed::FundingSigned;
 pub use gossip_timestamp_filter::GossipTimestampFilter;